Creeping buttercup identification and control

Ranunculus repens

Creeping buttercup is a low-growing, perennial species of buttercup originally from Europe and now found throughout North America and many other parts of the world. This competitive plant spreads by stolons and forms thick carpets on wet, poorly drained soils everywhere from farms to city gardens to natural wetlands.

Legal status in King County, Washington

Creeping buttercup is not on the Washington State Noxious Weed List. However, in King County, this non-native invasive buttercup species is classified as a Weed of Concern. For more information see Noxious Weed Lists and Laws.

The King County Noxious Weed Control Board recommends the prevention of spread of this species to uninfested areas and its control in protected wilderness areas, natural lands that are being restored to native vegetation, and in pastures that are being grazed.

Identification

Perennial with short swollen stems and creeping stolons that root at the nodes

Can be distinguished from other buttercup species such as tall buttercup (Ranunculus acris) by the creeping stolons

Can grow up to one foot tall but are often shorter in mowed areas

Leaves are dark green with light patches and are divided into three toothed leaflets, the central leaflet on a stalk

Pale patches on the leaves distinguish creeping buttercup from similar looking plants such as hardy geraniums

Basal leaves have long petioles (stalks), leaves higher up the plant have shorter or no petioles

Leaves and stems are somewhat hairy

Flowers usually have five (sometimes ten) glossy, bright yellow petals and grow singly on long grooved stalks

Bloom time is usually from March to August

Fruits are clusters of 20-50 achenes on globe-shaped heads. Achenes have a short hooked beak and are light brown to blackish brown when mature with an unevenly pitted surface

Impacts

Creeping buttercup's competitive growth crowds out other plants, especially in wet soils. One plant can spread over a 40 square foot area in a year. Creeping buttercup also depletes potassium in the soil and so can have a detrimental effect on surrounding plants. Because creeping buttercup can tolerate heavy, wet soils, it can be a particularly bad problem on well-watered lawns, wet meadows and poorly drained pastures. In addition to invading wet grassy areas, creeping buttercup is reported as a weed of 11 crops in 40 countries.

Fresh buttercup plants are toxic to grazing animals, who can suffer from salivation, skin irritation, blisters, abdominal distress, inflammation, and diarrhea. Fortunately, buttercup has a strong, bitter taste so animals generally try to avoid it if more palatable forage is available. Also, the toxin protoanemonin is not very stable and loses its potency when dry, so buttercup is not generally toxic in hay. Unfortunately, livestock occasionally develop a taste for buttercup and consume fatal quantities. It is safest to keep populations of buttercup under control on grazed pastures and offer plenty of healthy forage.

Growth and reproduction

Creeping buttercup spreads by seed and by long branching stolons that root at the nodes, forming new plants. In more established woodland and grassland communities, this plant increases mostly through stolons unless the soil is disturbed. In dry conditions, flowering and seeding is more prevalent and in wet conditions, stolons are more plentiful. Seeds can germinate and seedlings can grow under water-logged conditions.

One of the reasons creeping buttercup is so competitive is that its stolons respond to the environment. Under favorable conditions, plants form more stolons through branching. However, when nitrogen is limiting, stolons tend to be longer and unbranched allowing longer distance “sampling” of a number of potential sites until more suitable locations are found. When favorable conditions are discovered, stolon branching resumes, allowing rapid local colonization to take advantage of the available resources. In general, short stolons are produced in dense turf and much longer ones appear in open fields or woodlands.

Depending on the temperature, creeping buttercup either overwinters as a rosette or dies back to ground level. In either case, the nutrients stored in the short swollen stem produce rapid growth in spring, between April and June. Stolons grow from the leaf axils in spring and summer and growth peaks in late summer. Stolons connecting parent and daughter plants usually die off in fall.

Flowers can appear from March to August with seeds soon after. Each plant produces from about 20 to 150 seeds. Seeds can remain viable in the soil for at least 20 years, and up to 80 years, especially under acid or water-logged conditions. Seeds are dispersed by wind, water, birds, farm animals, rodents, and other animals by adhering to them with the hooked seeds.

Creeping buttercup grows particularly well in moist or poorly drained situations, although it will also colonize sandy and gravel-based soils with sufficient moisture. Creeping buttercup also has some tolerance to salinity and is found along beaches, salt marshes and the margins of tidal estuaries. In woodlands, this buttercup is mainly restricted to clearings, forest margins and paths. It is frost tolerant and will survive moderate droughts. Creeping buttercup is tolerant of trampling, compacted soils, and grazing.

Control

Be sure to have a long-term plan to ensure success, protect native and beneficial species while doing the control, and start in the least infested areas first and then move into the more heavily infested areas.

Prevention and cultural control

In lawns and pastures, promote healthy grass by overseeding, fertilizing as needed, and not over-grazing. Adding lime can improve grass health and keep buttercup from re-establishing. However, lime won’t control buttercup that is already well-established.

It also helps to improve soil drainage. Reduce compaction by aerating and avoid trampling when soils are wet.

Clean mowers and other equipment to avoid spreading buttercup seeds to un-infested areas.

Manual

Dig out with a sharp trowel or fork-type tool, removing all of the runners, roots and growing points. Digging is most effective from fall to spring while the soil is moist and roots won’t break off as much.

Cultivating or incomplete digging may increase the buttercup population because it can sprout from nodes along stem and root fragments.

Disturbance of the soil can increase seed germination. Seeds stay viable for 20 years or more and the number of seeds in infested soils can be immense compared to the number of plants present, especially in long-term pastures and woodland ecosystems.

Mechanical

Creeping buttercup’s growing point is at soil level, so plants resist mowing and quickly re-sprout when cut.

Regular cultivation can kill the buttercup but plants buried by cultivation can grow back up through deep soil and re-establish themselves and long-lived seeds in the soil can germinate and re-infest the area once cultivation ceases.

Chemical

Herbicides can be used if allowed and appropriate for the site and land use. Follow all label directions to ensure safe and effective use.

Glyphosate (e.g. Roundup, Aquamaster) can be applied to actively growing plants before they seed. Keep spray off of grass and other plants. Re-seed or re-plant bare areas after removing buttercup to keep it from re-infesting the area.

Broadleaf herbicides can be applied over grassy areas infested with creeping buttercup to selectively kill the buttercup and not the grass. Products containing the active ingredient MCPA are most effective on buttercup. Metsulfuron (Escort, Ally) is also effective but can harm some grasses. Follow label directions on timing and rates.

It will probably take at least two or three applications to eradicate creeping buttercup because of the seed bank and because some mature plants will generally recover.

Monitor the treated area for re-growth and pull up any new seedlings before they establish runners.

What to do if you find this plant in King County, Washington

Because creeping buttercup is so widespread, property owners in King County are not required to control it and we are not generally tracking infestations. We can provide advice on how to control creeping buttercup, but there is generally no legal requirement to do so.